Figured I'd get this one started. Right now the over/under on number of seasons this league survives is 1.5
Teams were announced this week:

Current head coaches include June Jones in Houston, Jim Zorn in Seattle, and Marc Trestman in Tampa Bay.
Stadiums look like a mashup of whatever was available. Smallest stadium seats 20,000 (Washington DC); largest is New York's Met Life Stadium at 82,500. 4 fields are grass, 4 are turf; One baseball stadium, Global Life Park in Arlington will be converted for football.

Season is ten games long. Players are paid on a per game basis. There is one designated "franchise player" who earns 25-60 thousand per game. The players salaries break down as follows:
Franchise Player (1): $25,000-$60,000 ($250,000-$600,000 per year)
Tier 2 Players (3): $15,000-$17,500 ($150,000-$175,000 per year)
Tier 3 Players (23): $6,000-$10,000 ($60,000-$100,000 per year)
Tier 4 Players (18): $5,000-$6,000 ($50,000-$60,000 per year)
Salaries actually look pretty good.

There are a number of proposals that the XFL are looking at for rule changes. Perhaps the key one (now confirmed as a rule) is ALL passes behind the line of scrimmage to have the same protocols of a lateral pass. This would allow for an additional pass over the line of scrimmage in any behind the line of scrimmage throw. It would also mean the ball would be live on any incompleted throws behind the line of scrimmage.

Key changes to the timing of a game to speed things up:
Other than change of possession, clock will run continuous, except for the last two minutes of a half. Play clock is 25 seconds, but from the end of the play (CFL is 20 seconds, but that is from the spotting of the ball from the official). Things could get crazy and really make substitutions difficult.

They are also tinkering with some CFL type rules including a five-yard zone on punt returns and defenses lining up one yard off of scrimmage.

Season begins the weekend following the Super Bowl in 2020.